1. Field of the Invention
The present invention relates to an arrangement for mounting an electric heating element in a furnace.
2. Description of the Related Art
Electrically heated furnaces or ovens that include a process tube in which objects are heated are known to the art. Furnace insulation comprised of high grade brick, such as aluminum oxide brick, is provided externally of the process tube and in spaced relationship therewith. Such a furnace, or oven, will normally have a generally circular cross-section and will typically operate at a temperature of around 1700° C.
The heating elements used are placed equidistantly around the furnace, and heating zones are positioned in the space defined between the outer surface of the process tube and the inner surface of the brick insulation. The contacts of the elements are placed outside the brick insulation, i.e., externally of the furnace. The electrical conductors of the elements extend through holes in the brick insulation.
The aforesaid space has a narrow dimension in the radial direction of the furnace and, hence, the heating zone of the elements is disposed parallel with the outer surface of the process tube. The length of the heating zone is significantly greater than the width of said space.
A serious problem with this solution is that the elements cannot be replaced from outside the furnace. It is therefore necessary to first cool down the furnace and then remove the process tube, in order to be able to reach and to exchange the elements. The elements are therewith removed by withdrawing them inwardly into the furnace. It will be obvious from this that the exchange of the elements is both laborious and complicated.
This problem is solved by the present invention, which provides an arrangement by means of which the elements can be replaced from outside the furnace and without removing the process tube.